The present invention is directed to a method and apparatus for venting air from a fluid system and, in particular, to a method and apparatus for venting air from a fire suppression wet pipe system.
Fire suppression wet pipe systems, such as water-based fire-sprinkling systems, fire suppression stand pipe systems, and the like, when placed in service and when occasionally drained in order to perform maintenance or changes on the system will have air in the piping network. When the piping network of the system is refilled with water, air becomes trapped in the system. This trapped air can cause internal corrosion of the piping network, especially when mild steel or galvanized piping is being used. Oxygen corrosion may be the predominant form of corrosion and metal loss within the fire protection system. Oxygen may enter the fire sprinkler system piping from two sources. First, oxygen may be dissolved in the incoming fresh water that is used to fill the fire sprinkler piping. Second, oxygen is present in any air that is trapped in the fire sprinkler system. Corrosion of mild steel fire sprinkler piping can, therefore, be most active when fresh oxygenated water and air are introduced into the piping during any drain and fill cycle. Draining and refilling the system allows additional corrosion. Each time the system is drained of the fluids and refilled, the high rate of oxygen corrosion that exists with a fresh supply of air will cause additional metal lost from the pipe walls.
To reduce the amount of internal corrosion within the piping network, the fire suppression wet pipe system is vented when it is filled or refilled. While this is commonly performed manually, an air vent valve may be connected at an upper portion of the system to automatically vent the air that rises to that portion of the system. Such air vent valves are configured to close after the air has been removed from the system to prevent any appreciable amount of fluid from being discharged. However, should the air vent valve fail, it may result in extensive discharge of fluid, which could cause water damage to the structure and any goods stored or displayed in the structure, such as a warehouse or retail space, especially if not discovered immediately. Indeed, for systems that operate at a high pressure, such as fire-sprinkling systems, a failed air vent valve may be capable of discharging a very large amount of fluid in a very short amount of time.